Sheet metal lagging



Nov. 25, 1941.

W. W. SMITH 2,264,100

SHEET METAL LAGGING Filed Nov.. 18, 1939 3 Sheets-Sheet l Nov. 25, 1941. w. w. SMITH 2,264,100'

SHEET METAL LAGGING f 'Filed Nov. 1'8, 1959 5 sheets-sheet 2 Z-f .4 J6 J3 /f `.Nov. 25, 1941. w. w..sM|TH SHEET METAL LAGGING Filed NOV. 18, 1939 5 Sheets-Sheet 3 plates, extending toward the center of the bore I2, and with their flat end portions positioned against the outer sides of the arched ribs I5 as shown.

As will be understood, the stress of the earth against these plates is inwardly and tends to inwardly deflect these plates and deform them at their ends along lines extending crosswise of the plate coincident with the ends 21 of the flanges 22. The desired resistance to such bending, however, is presented by the plate, by the double thickness of metal at the ends of the plate and the provision of the strengthening offset portions along the lines 214 and 26, while the deformed portions between the lines 24, 25 and 26 at opposite ends of the plate afford, with the adjacent infolded corner portions, board, flat bearing surfaces for seating the plate at its ends against the arched ribs I5.

By constructing the lagging plate as described,

it is possible to use relatively light gage metal without sacrificing the desired strength, and to performrat relatively slight expense the necessary operations on the sheet to produce the plate.

In accordance with the modification shown in Figs. `9, 10 and 11, the lagging plate, herein shown at 28, is formed of any suitable material, such as for'example sheet steel, provided of rectangular form. In producing this plate the corners thereof are cut off along the diagonal lines 29 and opposite edge portions of the sheet are bent along parallel lines 30 to extend angularly to the body portion of the sheet and form flanges 3l corresponding with the flanges 22 of the previously described plate. As the juncture of the flanges 3l with the body portion of the sheet along kthe lines 30 intersects the diagonal corner lines 29, the flanges 3I at their ends present the beveled surface indicated at 32 and reach short of the end edges of the sheet, as shown.

To stiften the ends of the plate against deformation in use as described of the plates I 8, the plate is deformed to produce offset portions 33 at each end of the plate, theseoffset portions,

preferably provided in pairs and converging toward the respective ends of the plate, and thus extending generally lengthwise of the sheet, ex-

tending from one side to the other of the points 34 of juncture of the flanges 3| with the body portion of the plate as shown and thus across those portions of the plate against which the most severe bending stress is exerted by the earth when the plates are positioned for use.

As will be noted, the angularly disposed flanges of both ofthe illustrated plates are flat; and

that by beveling the ends of these flanges the plates may be manipulated into set position behind the arched ribs without difculty as compared with plates in which the flanges present abrupt end edges.

While the construction of Figs. 9-11 does not appear to present the same degree of resistance to deformation at its ends when positioned for use as the construction shown in Figs. 5 and 6 when constructed of the same gage of sheet metal, nevertheless the fact that it may be manufactured economically and that it embodies the end stiil'ening feature of my invention renders it a desirable construction for use.

While I have illustrated and described certain particularv embodiments of my invention and have disclosed certain procedures involved in the manufacture of lagging plates, I do not wish to be understood as intending to limit my invention thereto as the structures shown may be variously modified and altered; and the invention embodied in other forms of structure, and the procedures for forming the plates varied, without departing from the spirit of my invention.

What I claim as new and desire to secure by Letters Patent, is:

1. A sheet metal lagging plate formed from a substantially rectangular sheet of metal with its corners bent back upon the body of the sheet at the same side thereof and opposite edge portions of the sheet and certain portions of said bent-back corners bent in the same direction as the corner portions and forming flanges extending angularly to the body of the sheet.

2. A sheet metal lagging plate having flanges at opposite edges thereof and portions integral with said flanges located at the inner sides of said flanges and overlying the ends of the plate, portions of the ends of the plate between said overlying integral portions being oset into the spaces between, and into substantially the plane of, said overlying portions.

3. A sheet metal lagging plate having yflanges at opposite edges thereof and portions integral with said anges located at the inner sides of said flanges and overlying the ends of the plate, portionsof the ends of the plate between said overlying integral portions being offset into the spaces between, and into substantially the plane of, said overlying portions, said flanges reaching short of the end edges of the plate and said offset portions extending from one side to the other of a line connecting the points of juncture of the ends of said flanges with the plate.

WALLACE W. SMITH. 

